The present invention relates to a suspension device for the support legs of platforms for facilitating oil drilling or oil production at sea, and more particularly relates to jack-up platforms.
Platforms of this type generally comprise legs which bear on the sea floor and a hull which is mounted on the legs so as to be movable along said legs.
The entire platform assumes a floating state at the drilling or production site and the legs are lowered until they contact the sea floor. Then the hull is raised above the level of the sea, by bearing against the legs, to an elevation at which the hull is out of reach of the highest waves.
The hull is therefore movable along the legs of the platform by raising mechanisms connected to said hull and including output gear pinions whose bearings are connected to the hull and which cooperate with racks mounted on at least a part of the legs. These gear pinions are driven by a plurality of electric motors operatively associated with speed reducers having a very high speed reducing ratio.
At the moment that contact occurs between a leg and the bottom of the sea, at the end of the descent, the impact may be very violent in view of the movement of the hull under the effect of the swell. These shocks are transmitted to the raising mechanisms and this subjects the multiple gears of the speed reducers to a very high stress.
In order to ensure the reliable operation of the gears of the speed reducers at the moment of contact between the legs and the bottom of the sea, it is therefore necessary to considerably over-dimension them or to await favorable weather conditions which increase the costs associated with the installation.